1. Field of the Invention
This invention is directed to an improved high speed labeler, and more particularly to such a labeler for labeling fruit, vegetables or other relatively small, discrete items. The inventive labeler is designed such that a specialized labeling web feed roller and a unique routing for the labeling web allow substantially increased labeling speeds over prior art labelers.
2. Description of the Related Art
Labelers for labelling fruit, vegetables and other small, discrete items traveling on a conveyor are well known. Such labelers are of four general types. Vacuum or "bellows" type labelers typically include a number of applicators arrayed about a circular head. Labels are stripped from a continuous web and, as each label is stripped, a respective one of the applicators picks up the label via a vacuum drawn on the applicator. As a piece of fruit approaches the circular head, the applicator applies an adhesive side of the label to the fruit and the adhesive overcomes the relatively weak vacuum such that the label adheres to the fruit. A second type of labeler is a "blow on" or compressed air labeler in which compressed air is triggered by the presence of a piece of fruit to be labeled, with the burst of air being directed toward an individual label which is then blown onto the fruit. A third labeling type is a "tamp apply" type in which labels are tamped onto the fruit with a piston-type applicator, with the label being released upon contact. Finally, a fourth type of labeler is a "laid-on" labeler in which a peel blade is positioned at the end of an articulating labeling arm. A continuous web of labels are threaded past the peel blade. The web is selectively advanced when a piece of fruit is sensed on the conveyor such that individual labels are stripped from the continuous label web by the peel blade at the exact moment that a piece of fruit is positioned beneath the peel blade. A sponge roller or the like is used to push the label into contact with the fruit. Laid-on type labelers are typically less complicated and therefore more economical than bellows, compressed air or tamp apply types. Of course, laid-on type labels also have no requirement for vacuum pumps or air compressors.
The present invention is directed to a laid-on type labeler. A primary goal of all labeling manufacturers is to increase the speed of a labeller without sacrificing accuracy and reliability. A problem with increased speed in prior art laid-on labelers is the fact that the label web is threaded through the peel blade at the end of the articulating labeling arm. The label web is typically selectively advanced by an intermittent drive motor. Such drive motors must be capable of virtually instantaneous starts and stops but the inertial effects of these quick starts and stops can place an undue amount of torque on the end of the articulating labeling arm. Furthermore, prior art label web drives have generally driven only the take-up side of the label web, i.e. the "waste web" left after the labels are peeled off by the peel blade. This practice of driving just the take-up side of the web path places differential pressure on the label web at the peel blade. As label web speed increases, this differential pressure often has the effect of tearing or breaking the label web at the peel blade.
Thus, in prior art laid-on labelers, labeling speed was effectively limited by the torque placed on the articulating labeling arm by high speed starts and stops and by the increased differential pressure on the web at the peel blade caused by a powered web take-up side. Typical maximum speeds for known prior art laid-on labelers are in the range of 300-400 pieces of fruit per minute.
Another drawback to prior art laid-on labelers has been the manufacturer's tendency to use specially designed control circuitry to control the labelers. This places the customer at the mercy of the manufacturer for continued support of the labeler.
It is clear then, that a need exists for a laid-on labeler which is capable of substantially increased speed over prior art labelers, e.g. on the order of 700 pieces of fruit per minute or greater. Such a system should minimize any torque placed on the articulating labeling arm by rapid starts and stops of the label web drive motor and should also minimize stresses placed on the label web at the point of the peel blade, both of which allow for increasing labeling speed. Finally, the inventive labelling system should use available "off-the-shelf" electronics for control circuitry whenever possible.